1. Field of the Invention
The present invention relates generally to a cooling system and more particularly, but not by way of limitation, to a portable therapeutic cooling system utilizing gas that provides a mild hypothermic effect adapted to be used immediately or as soon as possible following a traumatic event.
2. Description of the Related Art
There are circumstances in which it may be desirable to positively cool a patient as part of clinical treatment. Benefits may arise by subjecting patients who have suffered a stroke or cardiac arrest, or other significant or life threatening health event, to mild hypothermia, e.g. a temperature in the range of 32° to 34° C. for a period of more than about 1 hour after the cardiac arrest. Because the period of time from the significant or life threatening health event to when the patient's body may be treated may be great due to extraneous circumstances, such as transportation to a hospital, it is suggested that such treatment begin as soon as possible.
Temperature is an important variable in determining the amount of neural damage resulting from an ischemic attack (Dietrich et al, 1990). Clinically, temperature is now deemed a significant, independent risk factor for stroke (Reith et al, 1996), as well as a contributing risk factor to other risk factors for stroke such as hypertension, cigarette smoking, atrial fibrillation, diabetes, and transient ischemic attacks etc. Therapeutically, the implementation of mild hypothermia (34-36° C.) to stroke and head trauma patients is advocated as beneficial based on clinical studies (Kammersgaard et al, 2000; Schwab et al, 1997) and animal experiments indicating long term neural and behavioral benefits (Corbett & Thornhill, 2000; Colbourne & Corbett, 1994).
Clinically, whole body cooling of stroke patients has been tested with forced air-cooling with the Bair Hugger® wrap and anesthetics (Kammersgaard et al, 2000) or with cooling from fans and alcohol washes (Schwab et al, 1997). Pethidine anesthetic is given to prevent shivering activation. More regionalized head cooling of head trauma and stroke patients has been attempted. Cooling helmets (previously cooled or having cooled water or air circulating through them) attempt to decrease brain temperature via conductive changes through the skull (Klatz & Goldman, 1995 in U.S. Pat. No. 5,913,885; Gunn & Gunn 1998 in PCT Patent Application WO98/56310). Cooling pillows for the head and neck region have also been devised to decrease the body temperature of the patient (Tsutomu & Koji, 1998 in Japanese Patent Publication 09-072152; Katsumitsu & Shinichi, 2000 in Japanese Patent Publication 10-250455). These devices are often bulky and require specialized knowledge of the device in order to operate the device effectively.
Review of exemplary prior devices indicates that there is a need for a device or system that cools the entire body in conjunction with a temperature monitoring system so as to regulate the cooling effect. There is a need for a device that can be quickly applied to the patient shortly after a significant or life threatening health event. Such a device is particularly necessary in a pre-hospital setting, such as during transport in an emergency vehicle.
Further, prior devices are relatively bulky and uncomfortable. In the pre-hospital setting, for example, when a subject is being transported to a hospital after injury, there is a need for a device that is comfortable and respectful of the subject's physical condition. In the case of injury to the brain induced by stroke, or in the case of cardiac arrest, a subject may be transported to a hospital over a long distance. Many such subjects are elderly and would find it uncomfortable, traumatic or even undignified to be encased in such devices as are known. Particularly, bulky helmet-like devices with circulating fluids or large cooling inserts are inappropriate for this reason. Further, the sheer size of the known devices prohibit them from becoming a standard item kept in an emergency vehicle, or in any other pre-hospital setting having a limited amount of storage space. Prior devices further rely on infusions of cold saline, which suffers from a lack of temperature control during application of the infusion.
There is a need to have a simple, body-enclosing device that may be utilized by emergency medical technicians, health-service personnel, or in the patient's immediate area (e.g. home) that can cool the body to prevent damage to critical portions of the body and minimize any after-effects of such traumatic health events prior to reaching a hospital.